Water-cooled silencer



Aug. 1, 1950 R. B. BOURNE WATER COOLED SILENCER Filed March 12, 1947INVENTOR Aou/vo 6. 500/?6 BY $744 ATTORNEYS Patented Aug. 1, 1950WATER-COOLED SILENCER Roland B. Bourne, West Hartford, Conn, assignor toThe Maxim Silencer Company, Hartford, Conn., a corporation ofConnecticut Application March 12, 1947, Serial No. 734,113 2 Claims.(01. 181-43) This invention relates to silencers for the-exhau'st ofinternal combustion engines, particularly to such silencers as havecooling water introduced into the exhaust gas stream in such amanner'that water spray and the exhaust gases are'carried through thesilencer together. The purpose of the invention is to improve thesilencing efficiency of this type of silencer, while using few parts andthose of simple construction and light weight. The improved silencer isof particular value for such uses as the silencing of the engines ofsubmarines during surfacing, the silencer being flooded when thesubmarine submerges. Tests have shown that the silencer constructed inaccordance with the present invention will reduce the sound level of theexhaust 10 db below the best of the silencers previously available forthe purpose, while at the same time having a size and weight much lessthan such prior silencers.

The improved silencer operates upon a novel mode of coaction between anacoustic filter and gas-entrained cooling water. In the preferredembodiment the main channel through which the exhaust gas and coolingwater flows is coupled to one or more resonance chambers orsidebranches, and is fitted with means causing a substantial portion ofthe cooling water to be deflected into the sidebranches. The combinationof the effect of resonance in the sidebranches and the cooling and soundattenuating action of the water spray greatly increases the silencingefficiency both at high and low frequencies.

The extreme simplicity of the silencer is at once apparent from thedrawings, in which Fig. 1 is a median section taken longitudinallythrough the silencer;

Fig. 2 is a section on line 2-2 of Fig. 1; and

Fig. 3 is a detail plan of the downstream end of the inlet section ofthe main channel.

The silencer comprises a horizontally disposed cylindrical shell it!having an inlet header I I, an outlet header l2 and an intermediateheader l3 dividing the interior of the shell into two chambers l4 and15. Through the headers H, I2, and I3 pass respectively an inlet conduitIS, an intermediate conduit I1, and an outlet conduit l8. Collectivelythese conduits form the main gas and sound conducting channel, and theportions of the chambers I l and I5 not occupied by the conduits serveas resonance chambers or sidebranches acoustically and physicallycoupled to the main channel at the gaps l9 and 20 between the sectionsof conduit. Preferably these gaps are of a length between 70% and 100%of the diameter of the conduit, and are centered at a point betweenone-quarter and one-third of the length of the chamber measured from itsupstream end. The two chambers are preferably of unequal size to broadenthe band of frequencies attenuated by resonance, and their dimensionsare chosen to produce maximum attenuation of the major frequenciesoccurring the exhaust system of the engine to which the silencer is tobe fitted. To prevent shock excitation of the intermediate and exhaustconduits the former is pierced with antiresonance holes 2| located atthe half and quarter points of the conduit as fully discussed in UnitedStates Patent 2,265,342, and the outlet conduit provided with a slot 22preferably positioned on the bottom of the conduit to assist in drainageof the chamber l5.

The downstream open ends of the conduits l6 and I! are each fitted witha device which will cause water passing with the gas through the conduitto be deflected out into the chambers I4 and I5. This water ispreferably supplied to the gas during its passage through the inletconduit l6 through a series of holes 23 passing through the wall of thatconduit into an encircling housing 24 provided with a pipe 25 throughwhich water may be supplied from any desired source. Water enters theconduit simultaneously throughout its circumference and is carried awayby the current of exhaust gas in the form of a spray. The deflectingdevice is preferably in the form of a scoop 26 in the form of half acone with a apex angle. The deflectors extend about half way across theopen end of their associated conduits, and neither their size nor angleis particularly critical. They serve to deflect most of the entrainedwater into the sidebranches, although some water passes directly intothe next conduit section and some more passes out through a hole 21formed near the apex of the cone which is useful to permit rapiddraining of the conduits when the submarine surfaces.

The chambers l4 and 15 are vented to atmosphere through openings 28 sothat, upon submerging, these chambers completely fill with water,leaving no entrapped air which might disturb the trim of the vessel. Asmall opening 29 in the upper portion of the intermediate header l3 alsoassists in venting. The interior of the silencer is preferably coatedwith some protective material such as enamel, and by forming the shellIn in two parts joined by a gasketed flange 30 the internal parts aremade readily accessible for enamelling and at the same time provision ismade for holding the intermediate header l3 in place.

What I claim is:

1. A silencer having a substantially cylindrical casing, at least onetransverse partition dividing :5

said channel having a gap opening into each chamber intermediate thelength thereof, a water inlet delivering water into the channel-sat'aiipoint prior to the gap in one of the chambers, and a deflector locatedWithin each gap subsequent'to the point of waterintroduction-comprisinga -half...l5

cone whose axis is substantially coincidentwith that of the channel andWhOSBLhfllfbEliSBHiSJitCOa incident with half of the channel at theupstreamc end of the gap to throw into each chamber the water entrainedbythe gas entering said gap.

sound conducting channel positioned substan 2313;614-

tially- -tangent to theinterior of saidcasing at one side 'thereofandpassing-ina" substantially straight line through the'severalchambers-said ch'annel having a gap opening intoeach chamberintermediate' -thlength' thereof, "a water "inlet 4 delivering waterinto the channel at a. point prior to the gap in one of said chambers,and a deflector located within each gap subsequent to the point of waterintroduction comprising a half cone whose axis is substantiallycoincident with that of the channel and whose half base is coincidentwith half of the channel at the upstream end of thex-gap' to throw intoeach" chambenthezwater entrained by the gas entering said gap ina-"direction away from the line of tangency of the condi'tit and casing.

ROLAND B. BOURNE.

REFERENCES CITED Theiiollowing references are of record in the fil'e ofthis patent:

UNITED STATES PATENTS Number-=- Name Date 753,845 Brockway etal Mar. 8,1904 969,225 1 Walstromr Sept 6, 1.1910 984 ,2127 Gray Feb;: 14; 1911:

1,351,985 Andresenr. Semi-37,1920 1 ,'910;672:.- Bournev; -iMay-;23;"1933 Scarritt .Septl- #1940 2,328,161" Maxim .Aug.j:3l ,;1943:

I FOREIGN PATENTS Number Country Date;

432,372 Great Britain July-2531935 1 5

